the bible clearly states to 'abstain from blood'. There are many alternatives to blood and nowadays most surgeons prefer to use alternatives. In most cases where a transfusion takes place it is not even necessary. One of my best friends was told he would die without a transfusion, he rejected it, had EPO treatment instead, had his operation and has more or less fully recovered, the consultant (who was flown in from America) to perform the operation was stunned with his recovery, better than anyone who had ever gone through a similar procedure. Most of the post-operation complications come about because your body is busy fighting the foreign blood as well as trying to heal itself and so the body is run down. Another good friend (not a JW) is a surgeon, he has studied medicine for 8 years - he agrees that Blood Transfusion is an outdated practice and has told me himself that he would not have a transfusion nor would he allow his family to have one, the substitutes available now are far superior to transfusion and pose none of the post-operations threats that come from blood.
That is why we refuse transfusions, to some it appears hardline and somewhat insane, if you're not convinced try googling blood transfusion substitutes or words to that effect.
Finally, in agreement with paul Mather, referring to us as a cult is derogatory, our faith is based solely on gods word with everyone encouaged to look to gods word for guidance.